Research And Design About DC Voltage Of Statcom Based On Multilevel Voltage-Source Inverter With Separate DC Source

With the development of State Grid, reactive power compensation have been valued.The STATCOM based on the independent source cascade multi-level technology is with high reliability, good controllability, flexible application etc,It has already occupied an important position in the field of reactive power compensation. If the DC-side of STATCOM isn't stable, the output waveform of the STATCOM is poor, which could cause serious damage to the device and the whole grid. Therefore it's of significance to research the DC-side of STATCOM.In this paper, Two methods are proposed to balance the voltage of the DC-side of the STATCOM.The use of capacitor to balance voltage is the first method.The second one is using Z source inveter as the main circuit topology of STATCOM. In the aspect of theory, research and analysis the reason of the DC-side voltage unbalanced, and analysis of the different control methods. Simulator 7.05 is to verify the both of the methods, the simulator results prove that both methods are effective to balance the voltage of DC-side.Accroding to the design of the hardware and software, an experiment prototype of the STATCOM based on DSP and CPLD dual-core control has been made. The STATCOM of 500 Var capacity adopts SPWM modulation method. The STATCOM prototype is based on two 2H modules. The prototype has finished the experiments which are to verify the methods is effective, the results are that the methods are effective.